The invention relates to a device that is provided with a C-arm for the mounting of medical equipment, which C-arm is attached to a carrier so as to be adjustable along its circumference, said carrier being provided with a bearing block that is provided with at least one row of roller elements on both sides, the C-arm being constructed so as to be hollow and being provided on both sides with at least two oppositely situated internal running surfaces for the roller elements.
Devices of the kind set forth are used in practice for medical examination of a patient. To this end, an emitter of, for example, X-rays is attached to one end of the C-arm whereas a corresponding receiver is attached to the opposite end. The C-arm is adjustable inter alia along its circumference and hence can be accurately positioned relative to the patient who is accommodated on a table, for example, during a surgical intervention.
In order to ensure safe operation in all circumstances, the design of a device of this kind should satisfy a number of design requirements that are contradictory in some respects. First of all, the beam from the emitter to the receiver should remain within predetermined boundaries in all circumstances. This means that the C-arm should have a high bending strength. Furthermore, the construction of the device should be as light as possible so as to achieve an as high as possible degree of moeuvrability. This is of importance, for example, for the displacement of the device and for the manual adjustment of the C-arm. Moreover, the device should be capable of withstanding large temperature differences as they may occur, for example, during transport.
In order to satisfy the described requirements, the operation of the bearing system for the C-arm should be light and smooth in combination with a minimum amount of play.
A device of the kind set forth is known from DE 198 24 205. The cited document describes a device for medical applications that is provided with a C-arm on which an X-ray source is mounted at one side while a corresponding receiver is mounted at the other side. The C-arm is mounted so as to be journaled on a carrier. The bearing block is provided on both sides with a row of eight wheels. Oppositely situated wheels are coupled in a two by two fashion by way of a common rotary shaft.
The known device has the drawback that its wheels have a limited service life only. It has been found that notably the outer wheels are subject to accelerated wear that is due to the rigid connection of the wheels to the bearing block.
It is an object of the present invention to provide a device of the kind set forth in which the described drawback is eliminated.
To this end, the device in accordance with the invention is characterized in that a number of the roller elements of one row is interconnected by way of a connection member. The device in accordance with the invention offers the advantage that the forces are more uniformly distributed among the roller elements. Consequently, the individual roller elements are more uniformly subject to wear and the service life of the bearing block as a whole is prolonged. Moreover, it is likely that a smaller number of roller elements will suffice for each row. For example, it might be feasible to use six roller elements for each row. Alternatively, materials of lower quality can be employed so that the cost of the device is reduced in any case.
The roller elements of one row in a first preferred embodiment are grouped in two or more sets of roller elements, each set of roller elements being interconnected by way of a connection member. Each set of roller elements may comprise two or more roller elements. This embodiment represents an elegant implementation of the invention that utilizes few mechanical parts only.
The roller elements of one row are preferably interconnected in pairs by way of connection members. Laboratory tests have shown that this embodiment very successfully passes a test in respect of service life.
Oppositely situated sets of roller elements in a further version of the first preferred embodiment are connected in pairs to a common rotary shaft on both sides of the bearing block. The number of mechanical parts is thus further reduced.
The connection members of two neighboring sets of roller elements in one row in an alternative version of the first preferred embodiment are interconnected by way of a further connection member. Preferably, oppositely situated further connection members are connected in pairs to a common rotary shaft on both sides of the bearing block.
Each connection member in a further preferred embodiment is movable mainly in the plane of the C-arm. In this embodiment irregularities in the bearing surfaces are taken up better. Irregularities of this kind occur inter alia because in given positions the C-arm exhibits some degree of bending, that is, within predetermined limits; consequently, such irregularities are intrinsic to normal use of the device.
The bearing block in another embodiment yet exhibits a curvature that corresponds to the curvature of the C-arm and the rotary shafts are provided along the curvature. The C-arm can thus be smoothly moved along the bearing block so as to be adjusted to the desired position.
The bearing block in another embodiment is provided with a number of side roller elements whose rotary shafts extend mainly perpendicularly to the rotary shafts of the roller members and the C-arm is provided with a third running surface for the side roller elements. The C-arm is now suitably supported in the lateral direction during its movement along its circumference, so that undesirable pivoting movements in the lateral direction are effectively taken up.